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dmahon

Dehumidifier

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I installed a dehumidifier (ELA DD822)* in my observatory at the new year. It has been turned on permanently ever since - although there will be dew in the Summer, I guess it will disappear quickly as the air warms up - should I turn it off to sdave electricity and, perhaps, extend the life of the machine? Do you all keep yours running year round, non-stop (except when the roof is open)? It's costing me about £20 a month, which although noticeable on the usage graphs that the utility company supplies, when compared to last year, is a drop in the ocean compared to the cost of the kit it's protecting.

* anyone who wants one, see this discount code first.

Edited by dmahon

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Is it on a timer? Maybe knock the time off during daylight hrs?

£20/mth is a small price to protect not only your scope/mount, but also any electrical equiptment thats in there.

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Mine is on all the time but it is set at 50% humidity, if t drops below that it turns off (although the fan keeps running to circulate the air).

ChrisH

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Do you turn them off when the roof is open? Guess there are pointless when open?

Sent from my iPhone using Tapatalk

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Hi Dave,

Thank you for the thread, the discount code still works, just ordered mine!

Regards

Mike

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Trying to de-humidify the observatory 100% of the time might be a waste of money. Unless the observatory is horrifically damp all of the time, the only you should need one is for a few hours after a particularly dewy observing session- just to dry things up.

Typically my obsy is closed for many days at a time. I find a scattering of Poundland dessicant dehumidifiers works okay, especially in the drawers & cupboards.

$(KGrHqNHJCUE7zPq)sl-BPCH49Lw)!~~60_35.J

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I was wondering about the longevity of the dehumidifier when turned on permanently. I can set it on a timer, but the type of dehumidifier keeps going for a few minutes when switched off (to cool down) and loss of power wouldn't allow that.

Just wondering if it would do more harm to leave it on 24/7 or to turn it on remotely for an hour each morning.

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I think the only moving parts are the desiccant wheel and a small fan, longevity should not be a major concern - and the desiccant itself will deteriorate at a fixed rate I would think. So your major concern would be power consumption. Summer is just as bad as winter for high humidity, and warmer air will hold more water. I have one similar to yours so just set it at a fixed percentage humiditiy and leave it on (except when the obs is open to the outside air of course). Mine has suffered from an interminable rattle since new but apart from that has worked well.

ChrisH

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I guess this is a disadvantage of a dome obsy where there is no ventilation....  My roll-off roof has gaps all around which lets the air equalise even when really hot days (wooden obsy get very warm) - never had dew forming inside.

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If you want to know what conditions are like then leave some sacrificial bits of steel in there and keep inspecting them every now and then. If they go rusty it's too humid :)

ChrisH

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.... all my stuff in there is either steel or aluminium.... both are doing well :laugh:

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Based on this thread I bought mine this week for my new observatory. Discount code saved a few quid, thanks for the information.

Andrew

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I run mine during the winter only, or the summer occasionally if it's been bad weather.  

Carole 

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I run mine all the time I'm not imaging or observing all through the year. I only needed to see dew water running down the side of my EQ6 mount once to understand the need for protection against moisture. The cost of running it is worth every penny to ensure that my lovely gear remains in perfect condition, rust free with dry electronics.

Sent from my iPhone from somewhere dark .....

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is it worth installing a solar powered extractor?

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It may be but you'd have some serious hurdles. Peak power consumption of one of these devices is over 600 watt and that's a big PV panel. You're looking at some form of storage i.e. batteries and an inverter. I stayed at a cottage in Galloway that didn't have a grid connection and relied on PV and batteries, backed by a couple of diesel generators. A very nice system but a large investment.

Andrew

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Mine is set on 60% relative humidity on low power. When running it use around 300W/hour. (600W on high power)

Every hour the fan runs for about 5 min to check the RH (30W). If it is below 60% it will check it again in 1 hour. 

During wet days like now I get 1L of water each day. When the weather is better it takes several days to fill the tank of 2l.

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The instructions on mine (Peltier type) state that its efficiency falls as the temperature drops and anything below 10 degrees ambient it wont collect, (logical really). This is true, in winter it doesn't collect much at all so I only run it when conditions allow. I use a caravan crystal condensation trap for winter months. 

I would advise those looking for a dehumidifier to run all year round to check the specs, as running one that doesn't collect under 10 degrees throughout winter will not be much use unless you have a posh heated observatory :grin:

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Hi, I live in Southern Ontario. I have 10 ft by 10 ft RON obs. I keep my EYES mount in there all year. I bring in the OTA. But what I do to keep the moisture out of my mount, is I covered it with a large towel, and then a cover made of heating duct foil. ( the insulated type ) In the cold months I keep light bulb on a dimmer under the cover. This ensures the mount is warmer than the surrounding air. So if the temperature rises I do not get condensation on or in the mount. I have done this for 6 years, with no problem with the mount. Orion 77

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Well, in the end I set at LOW and 60% humidity and ran it all year as advised by the company that sells them (and gives the discount) - and all was working fine until a few weeks ago.

I've asked them for any advice but I suspect they will be having a well earned break, so I thought I would also ask on here. Recently the dehumidifier has stopped and the "water full" light has indicated. Looking at it, the water tank has indeed been full and I have had to empty it. This is a surprise as I have a hole drilled through my observatory wall and the supplied pipe attached to the nozzle. The pipe has a decent fall*, has been working all year and there has been no freezing weather down here - not even a frost! Most of the time it has been above 7 degrees, so my winter tyres have been entirely wasted. I had no similar problems last year in January/February when the weather was much colder. There are no kinks to the pipe and no obstructions.

The machine is just under a year old. Is this a fault or am I missing some simple instruction that will make it work correctly?

* and I have increased it further by standing the dehumidifier on a plank of wood.

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Couple of questions, is is designed to run 24/7 for a year, is it a quality type of unit or cheapest that could be found, if the warranty covers it send it back if it doesn't buy a different brand, fixing it your self is a option if you can buy the replacement sensors ect....Good Luck and a Happy New Year.....The brand and Model posted might help with repairs or suggestions...

Edited by Tinker1947

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I've seen the tank full a few time with mine. If it happens I empty it and the unit continues to function. I'm not sure why this happens but I've reduced it's frequency by shortening the pipe and ensuring that it's got a continuous drop to the drain in the floor.

Andrew

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I have had this once (mine runs to the outside too). In my case it was simply a slight rise in the outlet pipe after I had changed its position to stop it blowing through the outlet vents onto my mount - the water is not pumped out, it is a gravity waste system so any impediment will allow the water to over spill into the tank until it fills up and turns the unit off.

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Remember that rust is not the only problem created by humidity - fungal growth on optical glass elements (lenses and mirrors) must also be avoided.  I think the usual recommendation for fungus prevention is to keep the humidity below 50%.

Mark

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